Collision induced dissociation: A statistical theory

Abstract

A statistical theory of collision induced dissociation using the three body angular momentum introduced by Delves and Smith is presented. A distinction is made between direct dissociation (no two body intermediates) and indirect processes, due to the formation of quasibound diatoms (of either the chaperon or the energy transfer type). The post‐threshold energy dependence in the statistical theory is of the type ${\mathrm{A(E-E}}_0{)}^n{\mathrm{/E}}_{\mathrm{tr}}$ where E is the total energy and E_tr the translational energy. $\text{(n ≈ 2}$ or 1.5 for direct and indirect processes.) The threshold energy, E_o, can be determined by a suitably linearized plot without a prior determination of n. Following a series of diagnostic calculations for the reaction $\mathrm{He}+{\mathrm{H}}_2^{+}\mathrm{(\nu )\to }\mathrm{He}+{\mathrm{H}}^{+}+\mathrm{H}$ , the experimental results are simulated via the introduction of a nonstatistical (i.e., selective) bias by representing the dependence of A on the initial vibrational energy in the form $\mathrm{A\; \propto }\exp {\mathrm{(-\lambda \; f}}_{\nu })$ where f_v is the fraction of enegy in the vibration.